Realization of rapid synthesis of H-ZSM-5 zeolite by seed-assisted method for aromatization reactions of methanol or methane

Abstract

H-ZSM-5 zeolites are successfully synthesized within 1 h with organic-template-free system by the seed-assisted method. The synthetic method not only reduces the production cost of H-ZSM-5 zeolite, but also prevents the pollution of environment compared with the conventional synthesis process. Characterization by SEM, XRD, N2 adsorption-desorption, NH3-TPD and Py-IR confirms that the product of H-ZSM-5 with a high crystallinity and reveals that the rapid synthesis process in accordance with seed surface crystallization mechanism. In order to improve the aromatic selectivity on H-ZSM-5 zeolite, different concentrations of Mo and Zn catalysts were prepared by incipient wetness impregnation and ion-exchange method. Mo-Zn/H-ZSM-5-SAS-1 h have similar catalytic lifetime and higher selectivity of paraxylene in aromatics products compared with Mo-Zn/H-ZSM-5-seed in the reaction of methanol to aromatic. However, the catalytic lifetime of 6%Mo/H-ZSM-5-SAS-1 h is shorter than that of 6%Mo/H-ZSM-5-seed catalyst in methane to benzene reaction under same reaction conditions.